Key points are not available for this paper at this time.
A widely used assumption within the gravitational-wave community has so far been that a test mass acts like a rigid body for frequencies in the detection band, i.e. for frequencies far below the first internal resonance. In this paper, we demonstrate that localized forces, applied for example by a photon pressure actuator, can result in a non-negligible elastic deformation of the test masses. For a photon pressure actuator setup used in the gravitational-wave detector GEO 600, we measured that this effect modifies the standard response function by 10% at 1 kHz and about 100% at 2.5 kHz.
Hild et al. (2007) studied this question.